So I have had my phone since the middle of May, been updating it while possible and all that. I have noticed, however, that the actual volume when the volume slider is maxed out changes sometimes, I have only noticed it on the media volume. I haven't noticed any correlations with anything else. It's basically like it changes between a loud and a quite mode, so I've only experienced two different "max volumes"
Edit: it has changed in the middle of songs, and I have noticed the same songs playing at different volumes.